On Dangerous Ground by Jack Higgins (Paperback) Berkeley Press 1995. Book VG Plus,

Sean Dillon, the elusively brilliant terrorist turned hero of that adventure, in a complex story blending history, government secrets, duplicity, and murder. As Hong Kong prepares to be restored to China in 1997, powerful business interests - including the Mafia, which has invested billions in the city - brace for the ramifications . . . and will do anything to stop the lease from expiring. In London, Brigadier Charles Ferguson, head of the prime minister's personal action unit, has learned of the existence of a copy of the mysterious Chungking Covenant. This document, long thought lost, was signed in China in 1944 by Mao and by Lord Mountbatten on behalf of Winston Churchill. In return for arms and assistance in his war with the Japanese, Mao agreed to extend the Hong Kong Treaty by one hundred years if he ever came to power in China. Halfway around the world, sinister Hong Kong business interests have also learned of the newly discovered document. If the Chungking Covenant were to become public, the delicate balance of power among the Chinese, British, and Americans would be destroyed. Dillon and Ferguson, on direct orders from the prime minister, must stop the document from coming to light at all costs. The story accelerates with deadly momentum, climaxing in a shocking display of violence at the Scottish castle of a mysterious American billionaire, a castle known as Loch Dhu, or "Place of Dark Waters.